Wheels in the sense of the present application essentially consist of a wheel rim and a bearing bush and can be designed, for example, as a number wheel or as a gearwheel for the construction of a numerical counter, such as, for example, in a water meter. The rim of the wheel encloses the mostly centrally arranged bearing bush, by means of which the wheel can be supported on an axle or shaft. The bearing bush frequently is made of a metal, while the wheel rim is made of a plastic. However, this combination of two different materials with deviating material properties, such as, for example, differing shrinkage behavior in the wheel, leads to wear phenomena, in particular between the bearing bush and the wheel rim or within the bearing bush.
It is known that the wear between the plastic of the wheel rim and the bearing bush can be reduced by using plastic bushings. For instance, WO 2012/130304 A1 describes a wheel with a toothed rim, in which both the toothed rim and the bearing bush are made of a composite material. The toothed ring and the bearing bush are connected to one another in a rotationally fixed manner by means of positively locking elements, the bearing bush being also mounted so as to slide on an axle. Admittedly, the use of the same basic material facilitates the production of the wheel. However, the material properties of the bearing bush and the toothed ring can be adapted only to a limited extent to their functions.
WO 96/15380 A1 also describes a wheel in the sense of the present invention with a wheel rim, made of a thermoplastic material, and discloses a bearing bush of the wheel consisting of a metal or of a plastic material. In the production process of the wheel, the wheel rim is first of all produced by casting the heated, thermoplastic material in a mold, the mold, in particular, having a central recess for the bearing bush and the prefabricated bearing bush being inserted into this central recess of the wheel rim during the cooling process. During the cooling process, the bearing bush is firmly enclosed by the wheel rim. Additional brackets on the wheel rim increase the connecting effect of the bearing bush within the recess of the wheel rim, so the bearing bush and the wheel rim are connected firmly with one another. This manufacturing process, in particular, has the disadvantage that the bearing bush must be prefabricated and additional brackets are required for a good hold of the bearing bush within the wheel rim.
The solutions in the above-mentioned prior art have the disadvantage that wear phenomena can occur at the bearing bush and the axle due to the rigid connection between the wheel rim and the bearing bush.
U.S. Pat. No. 4,012,961 has disclosed a deflection roller for a cable pull of textile curtains. The roller consists of two prefabricated plastic parts, the two plastic parts being made of the same material and the plastic parts have guide means in the form of an elevation, which is raised in cross-section, and a bulging molding, which can be brought into engagement therewith. The two parts are connected to one another by compression, as a result of which a snap-on or latching connection is provided. The inner plastic part and the outer plastic part are then rotatably movable relative to one another in the direction of rotation relative to the guide extending in the direction of rotation. The production of the roller is costly. The handling of the semi-finished products, that is, the comparatively small prefabricated plastic parts, is also not easy. Furthermore, it is possible that the roller may break in use in the event of mechanical loads acting in the axial direction. The snap or latching connection finally also has the disadvantage that a precise positioning of the two plastic parts relative to one another is not ensured, particularly in the case of mass production. A wheel manufactured in the manner described is therefore also not suitable as a counting wheel for a meter.